This invention relates to an extensible positioning device of the shank of an umbrella, particularly to one firmly keeping the shank at one of many adjustable positions without fail.
A conventional adjustable shank of an umbrella shown in FIG. 1 includes an inner tube 10 and an outer tube 20 for the inner tube to telescope therein, and an eccentric fixing grip 201 located at a proper point of the outer tube 20 for compressing the inner tube 10 to keep the inner tube 10 immovable to the outer tube 20. If the fixing grip 201 is released, the inner tube 10 can freely telescope in the outer tube 20 so as to adjust the whole length of the shank.
However, the fixing grip 201 in the conventional adjustable shank forces inward the inner tube 10 only at one point, so its compressing force may often not be enough to stop the inner tube 10 from moving after fixed, causing the inner tube move down gradually to shorten the shank.
The objective of the invention is to offer an extensible positioning device of the shank of an umbrella capable to keep an inner tube at an adjusted position relative to an outer tube firmly without possibility of the outer tube moving down to shorten the shank as the conventional one does.
The feature of the invention is an outer tube, an inner tube telescoping in the outer tube, and an adjusting cylinder and a fixing cylinder fitting around the outer tube and screwing with each other so that the adjusting cylinder may screw tightly inward the fixing cylinder so that compressing members of positioning arms of the fixing cylinder may move in holes in the outer tube and then further compress the inner tube tightly to keep the inner tube at an adjusted position relative to the outer tube.